1. Field of the Disclosure
The present disclosure relates to an organic light emission display having single crystalline silicon thin film transistor (TFT), and a method of fabricating the organic light emitting display.
2. Description of the Related Art
In active color image display devices using organic light emission diode (OLED), each of a plurality of pixels is formed of a circuit including two transistors and one capacitor. That is, the circuit for each pixel includes a switching transistor for sampling an analog image signal, a memory capacitor storing the image signal, and a driving transistor controlling electric current supplied to the OLED according to voltages of image signals accumulated in the memory capacitor. The above circuit is referred to as two transistors-one capacitor (2T-1C) structure, and an example of the circuit having the 2T-1C structure is disclosed in Japanese Patent Publication No. 2002-156923. The pixel having the 2T-1C structure can be realized on a complementary metal oxide semiconductor (CMOS) that is obtained from a wafer, that is, single crystalline silicon wafer, and it is difficult to realize the 2T-1C structure pixels in a thin film transistor (TFT).
When the OLED is formed on a glass or a plastic substrate, polycrystalline silicon TFT is used. The polycrystalline silicon has low uniformity, and thus, an additional compensation device is required in order to form the OLED using the polycrystalline silicon TFT. For example, a voltage program (Sarnoff, SID98) that directly compensates driving TFT and a current program (Sony, SID01) that determines current value of the OLED using a current mirror circuit are suggested for compensation. Various other compensation units have been suggested, however, these circuits tend to become complex due to the compensation device and it is difficult to design the circuit including the compensation device. In addition, the compensation device causes some problems.
Single crystalline silicon is useful for a system on panel (SOP) structure, in which a system is formed on a display panel. The mobility of single crystalline silicon is 300 cm2/Vs or higher, and thus, a high quality switching device used in a display device can be obtained from single crystalline silicon having high mobility. However, single crystalline silicon cannot be used on a substrate that has a poor response to heat, such as a plastic.